a) Field of the Invention
The present invention relates to an improved blood sampling device also known in the trade as a"lancet injector", that can be used in combination with a lancet and an isolating platform to obtain blood samples for diagnostic purposes in a very safe and accurate manner.
The invention also relates to the combination of such a lancet injector with a lancet and an isolating platform especially adapted for use therewith.
b) Brief Description of the Prior Art
Lancets are well known devices commonly used in the medical field to make small punctures in a patient's skin in order to obtain samples of blood. Lancets usually comprise an elongated plastic body from which projects a sharpened metal needle covered by a protective cap that is removed before use of the needle to puncture the skin (see, by way of non-restrictive example, U.S. Pat. No. 3,358,689 to HIGGINS).
Lancet injectors are also well known devices that are used to "fire" or project a lancet toward the skin of a patient in order to puncture the same in an accurate, standardized and consistent manner.
Such devices have originally been devised for use by the patients themselves, who have to puncture their own skin on a regular basis and are afraid or reluctant to do so"manually". However, they are now commonly used by professional medical staff, essentially because they make the duration and depth of penetration of the lancet needle through the skin very short and small and serve to shield the patient from viewing the actual skin piercing act, and thus to minimize pain and trauma associated with the process.
In the recent years, numerous patents have been granted on lancet injectors which are of different and improved structures. All these known lancet injectors use metallic or leaf springs to push the lancet forward upon actuation and then retract it immediately in order to minimize pain sensation (see, for example, U.S. Pat. Nos. 4,203,446; 4,469,529; 4,527,561; 4,677,979 and 4,889,117).
Some known lancet injectors are also provided with means, usually in the form of a screwable ring or separable multiple sized adaptor caps, to control and adjust the depth of penetration of the needle of the lancet (see, for example, U.S. Pat. Nos. 4,469,110 and 4,895,147).
Some other known lancet injectors are provided with means for allowing ejection of the lancet after use without having to seize it with the fingers to do so. Such is achieved either by use of mechanical ejecting means (see U.S. Pat. No. 4,976,724) or by use of a separate disposable isolation cap operatively connected to the lancet in such a manner as to act as a protective hood for its needle (see U.S. Pat. Nos. 4,990,154 and 5,074,872). The basic idea behind this last generation of lancet injectors is essentially to make them safer in use by the medical staff who is more and more concerned with the risk of disease transmission in the case of accidental puncture with a used lancet and resultant exposure to contamination through the trace of blood left on the used lancet.
In Applicant's U.S. Pat. No. 5,324,303 referred to hereinabove, there is disclosed a combined, single-use, disposable lancet and multi-function cap, in which the multi-function cap is so devised as to be useful in the following four separate and distinct functions.
First function: The multi-function cap serves as a protective cap (or sealed barrier) to keep the sharp needle of the lancet protected and sterile after moulding and prior to being twisted off to reveal the needle for actual use.
Second function: The multi-function cap serves as an isolation cap (or physical intermediary) when the lancet is being used with a lancet injector such that no physical part of the actual injector itself may come into contact with the target area of the patient's skin from which blood is to be drawn. Only the multi-function cap makes physical contact with the target area of the patient's skin from which blood is to be drawn.
Third function: The multi-function cap serves as a means of controlling depth of penetration when the lancet is being used with a lancet injector such that the user has variable options of depth to which the lancet may be allowed to penetrate the skin.
Fourth function: The multi-function cap serves as a protective cap (or locking hood) to cap and permanently lock the used sharp lancet needle "within" the cap immediately upon ejection and discarding of the used lancet, thus serving to protect users and medical professionals against the risk of accidental finger puncture once the lancet has been used (fired). Simultaneously, the multi-function cap serves to prevent the lancet from being fired accidentally for a second time.
The fact that the multi-function cap is not only acting as a protective cap to keep the needle sterile before use, but also as an isolation cap, a depth penetration barrier and a locking needle hood, is of a great interest as it eliminates the need for an extra isolation cap and it economizes both in manufacturing cost and in required amount of plastic material.
In former U.S. Pat. No. 5,324,303, a blood sampling lancet injector is also disclosed, for use with the above mentioned combined lancet and multi-function cap. This lancet injector is devised to reduce the danger of accidental finger-stick from a "used" blood contaminated lancet needle, thanks to the presence of ejection means which automatically ejects the lancet in concert with the multi-function cap that firmly grips onto the lancet at a predetermined position where it may acts as a protective locking hood for the needle after the injector has been "fired" and the used lancet is ejected to be discarded.
Thanks to the multi-function cap used therewith, the blood sampling lancet injector also allows for easy regulation of the depth of skin penetration in a positive and reliable manner for the purpose of obtaining a blood droplet or sample of optimum volume while simultaneously serving to diminish as much as possible patient discomfort.
In this connection, it is known that normal average desirable penetration to produce sufficient blood for glucose content measuring purposes as required for instance by most diabetic patients, is around 0.040". For young children, a penetration 0.025" to 0.030" is sufficient and provides less discomfort while for some adults who have a thicker than usual epidermis, up to 0.090" may be needed to produce an ample blood droplet. The invention disclosed in U.S. Pat. No. 5,324,303 provides for all penetration depths within these two extremes with a lancet having just one given needle length, the required depth being easily adjusted in a very reliable manner by mere rotation of a depth indicator that forms part of the multi-function cap and is provided with an easy-to-read scale giving different comfort depth values, in order to reduce as much as possible discomfort.
The blood sampling lancet injector disclosed in U.S. Pat. No. 5,324,303 is also interesting as compared to the previous lancet injectors in that it eliminates the use of metallic springs, and uses instead an elastomeric band which is suitably restrained at four points so as to provide a unique two-way, well cushioned prime mover providing both for very rapid skin piercing and speedy withdrawal of the needle, which serve to minimize patient discomfort.
Thus, U.S. Pat. No. 5,324,303 discloses a blood sampling lancet injector which incorporates each and all of the above mentioned features and thus:
is much less complicated than the prior art devices which require the use of metallic springs that are far more costly than the elastomeric band used herein; PA1 is much safer than the prior art devices which do not provide for disposable isolation caps, the injector not only obviating cross-contamination but also allowing for instant regulation of the depth of skin penetration and protective hooding and locking of the needle after use to eliminate the possibility of "second firing" without employing any extra components; and PA1 is much less expensive to manufacture than the prior art devices which, for most, require costly assembly operations that may include sonic welding, gluing and/or screwing, the invention, in complete contrast, providing for rapid low cost assembly with all components suitably shaped to rapidly click together either by hand or a robotic assembly machine. PA1 a structure which requires the use of metallic springs that are far more costly than the elastomeric band used herein; PA1 a structure which is much safer and efficient than the prior art devices, the invention not only obviating cross-contamination, but also allowing for instant regulation of the depth of skin penetration and protective holding and locking of the needle after use to eliminate the possibility of "second firing" without employing any extra component; and PA1 a structure which is much less expensive to manufacture than the prior art devices, because it provides for rapid low cost assembly with all components suitable shaped to rapidly click together either by hand or a robotic assembly machine. PA1 a longitudinal axis; PA1 a front open end hereinafter called "mouth" on which the isolating platform can be detachably fixed; and PA1 a rear end. PA1 a forward end integrally connected to a launching socket in which the lancet to be injected is detachably insertable; PA1 a first abutment at a first distance rearward the launching socket; PA1 a leaf spring at a second distance rearward the abutment, this leaf spring projecting forwardly outwardly from the shaft and being lockingly engageable with a stop provided in the rear slot of the chassis when tile shaft is moved rearwardly within the passage; and PA1 a rearward end defining a second abutment. PA1 a forwardly projecting stem that is slidably movable within the launching socket through a rear opening provided in the same; PA1 an operating knob projecting out of the chassis through an elongated opening provided in the same opposite to the front slot; and PA1 a small hook opposite to the knob, this hook being slidably engageable into the front slot of the chassis. PA1 a resilient front tip that is engaged by the hook of the ejector when this ejector moves from a maximum forward position to the rear; PA1 a lower rib that projects downwardly and is slidably engaged into the rear slot of the chassis; and PA1 a rear edge. PA1 during the loading step, the pressure exerted on the knob causes the pins to engage the notches made in the angulated slots of the chassis and be locked therein; PA1 during the cocking step, the angulated slots cause the lancet ejector to move away from the front tip of the slide member and thus to avoid any interference with the same until the injector is fired; PA1 during the firing step, the angulated slots cause the lancet ejector to move toward the front tip of the slide member and its hook to engage said front tip rearwardly of the same and to push said slide member forwards; and PA1 during ejecting step (iv), the angulated slots cause the hook of the ejector to deflect the front tip of the slide member and to pass in front of the same, thereby causing the ejector to push back the slide member when it moves rearwards under the action of the second elastomeric band. PA1 when the lancet injector is in its loading position, the second color is displayed through the window; PA1 when the lancet injector is in locked position at the end of cocking step, the first color is displayed through the window, thereby indicating that the injector is ready to be fired; and PA1 when the lancet injector has been fired but the lancet has not been ejected yet, the third color is displayed through the window, thereby giving a warning signal that the ejector contains a used lancet which should immediately be ejected. This third color display remains locked until the lancet is ejected and the mechanism restores itself to rest at which time it changes back to first color. PA1 an elongated body of a given diameter that is snugly insertable into the launching socket of the lancet injector; and PA1 an axial needle embedded into the body, this needle having a sharp end projecting out of the body at a given distance away from one end of the same. PA1 a front plate that extends transversally to the mouth of the chassis when the isolating platform is connected thereto, the plate having a given thickness and a central through-hole of a diameter smaller than the one of the body of the lancet so as to stop this body while allowing the needle of the lancet to pass through the through-hole and to project out of the plate when the injector is fired; and PA1 a fixation sleeve coaxial to the plate and sized to snap onto the mouth of the chassis so as to detachably connect the isolating platform to this mouth.